FIG. 1 is a perspective view showing a structure in which a conventional underwater pump is installed. As shown in FIG. 1, a supporting frame 1 is mounted to the top of a water tank (not shown), and an elbow pipe 2 is mounted on the bottom of the water tank. To the supporting frame 1 is attached a bracket 9, by which the upper ends of a pair of guide bars 3 are fixed to the supporting frame 1. The lower ends of the guide bars 3 are attached to the elbow pipe 2. At one side of an underwater pump 4 is connected a guide member 5. When the underwater pump 4 is to be installed under the water in the water tank, a pulling rope 6, which is connected to the underwater pump 4, is moved down by means of a hoist (not shown). As the pulling rope 6 is moved down, the underwater pump 4 moves down due to its own weight while being guided along the guide bars 3. After the underwater pump 4 moves down along the guide bars 3, a flange 7a formed at an outlet 7 of the underwater pump 4 is connected to another flange 2a formed at an inlet of the elbow pipe 2. As a result, the outlet 7 of the underwater pump 4 communicates with the elbow pipe 2.
When the underwater pump 4 is energized through a power line 8, the underwater pump 4 is operated. When the underwater pump 4 is operated, the water in the water tank is discharged to the outside via the outlet 7 of the underwater pump 4, the elbow pipe 2, and a discharging pipe (not shown) connected to a flange 2b formed at an outlet of the elbow pipe 2.
FIG. 2 is a front view, partially in section, showing connection of a conventional underwater pump and an elbow pipe.
As shown in FIG. 2, to the upper side of the inlet of the elbow pipe 2 is fixed a supporting bar 25 while the right and left ends of the supporting bar 25 are extended outwardly. To the flange 7a formed at the outlet 7 of the underwater pump 4 is connected the guide member 5.
The guide member 5 comprises: an annular hollow part 51 having a central opening 52 formed therethrough for communicating the outlet 7 of the underwater pump 4 and the inlet of the elbow pipe 2 to each other; a projection part 54 having an inclined surface making contact with the inner side of the supporting bar 25; and a guide part 55 disposed between the guide bars 3 in such a manner that the guide part 55 is vertically movable along the guide bars 3. The outer side of the annular hollow part 51 of the guide member 5 is vertically disposed. Similarly, the outer side of the flange 2a formed at then inlet of the elbow pipe 2 is vertically disposed.
In the case of the above-mentioned connection of the conventional underwater pump 4 and the elbow pipe 2, however, a reaction force (A) is applied to the underwater pump 4 in the direction opposite to the elbow pipe 2, and a pressure (B) caused by the sum of the weight of the underwater pump 4 and the pressure of the water in the water tank is also applied to the underwater pump 4 in the lower direction of the underwater pump 4 when the underwater pump 4 is operated. Consequently, the underwater pump 4 and the guide member 5 are upwardly rotated counterclockwise about the supporting bar 25 by means of a resultant force (C), which is the sum of the reaction force (A) and the pressure (B). As a result, there is a gap created between the lower side of the annular hollow part 51 and the lower side of the flange 2a formed at the inlet of the elbow pipe 2, and water leaks through the gap.